Pasture Watch
How to sweep away broom
Why is it a weed?
Prolific, outcompetes pasture species
Where is it found?
Nationwide
Is it toxic?
No
Positives
Fixes nitrogen in soil, pollen- and nectar-rich flowers which can be used to make a potent wine
GORSE is one of NZ's most troublesome weeds. It's a nitrogen-fixer, loves our climate, easily colonises pasture, and forms dense bushes, making it hard for stock to control it.
Broom (Cytisus scoparius) shares all of those attributes, but it also tolerates cold weather, making it a big problem in cooler parts of the country. It will even dominate gorse.
Broom stems look like a broom head and are almost leafless. In its second year of growth, it produces beautiful yellow flowers, usually between September and April. They're a rich source of pollen and nectar for bees and bumblebees but then produce explosive seed pods which scatter the seeds up to 5m away.
The seeds can survive for decades in the soil. Research has found in some forestry areas there are as many as 36,000 broom seeds per square metre.
How to control it
Sheep and goats love to graze broom seedlings and can significantly reduce its spread.
It's essential to improve soil fertility and sow fast-growing ryegrass and clover varieties to out-compete broom seedlings.
Slashing and burning give good control, but new pasture must be sown quickly afterward and then grazed to help control any re-growth.
Cutting plants down and applying herbicides to the remains is an effective strategy, but may not be possible if the broom is growing in hard-to-reach areas.
Some selective and non-selective herbicides are suitable, but it's vital to get advice on the best option and timing for your block.